Antibodies to various kinds of collagen will be searched for in subjects with rheumatoid arthritis and in various controls (normals and patients with other forms of arthritis and other chronic diseases). The significance of these antibodies will be ascertained; namely, whether they are the cause, effect, or merely serologic markers indicating genetic predisposition to development of rheumatoid arthritis (RA). Patients and their families will also be typed for the newly discovered allotypic markers, since typical rheumatoid factors are IgM. Studies designed to demonstrate and quantitate suppressor T-cells in peripheral blood of infra-human species are being attempted; if successful, we hope to apply this to peripheral blood of normal humans and of patients with RA.